This invention relates to apparatus for measuring height variations in a surface and more particularly, but not by way of limitation, relates to apparatus for measuring faulting in a surface from a moving vehicle.
Various types of roadway surface condition evaluation systems are known. For example, the assignee of the present invention has a video inspection vehicle which will video the surface of a roadway and collect rutting and roughness data using ultrasonic sensors and accelerometers. A computer is used to load, manage, verify, edit, and save the information recorded about the roadway. However, the known system will not accurately measure the height of surface variations in the roadway.
A common problem related to the height of surface variations is called faulting. Faulting occurs in concrete slab roadways and at joints in roadways and bridges. For example, it is common to find faults at concrete slab joints, bridge expansion joints, bridge approach slabs, breaks or cracks in the roadway, and the like. Although the assignee's previous system will detect the presence of faults, it will not accurately measure the height of faults and other variations in the roadway surface. It is desirable to be able to accurately measure and record faults and other height variations in a roadway surface from a moving vehicle in order to facilitate and reduce the cost of maintaining roadways. That is, in order to be able to assess the severity of faulting and surface deterioration in roadways, determine whether maintenance is required, and accurately locate where the maintenance is required, it is necessary to be able to accurately measure faulting and other surface height variations from a moving vehicle.
Therefore, there is a need for apparatus and method for measuring height variations in a surface, such as a roadway, from a moving vehicle. There is also a need for such a sensor which will compensate for vertical motion of the sensing device and vehicle with respect to the surface.